Dial system with limit and lock for multiturn shafts



Oct. 27, 1959 R. KALOUS 2,909,933

DIAL SYSTEM WITH LIMIT AND LOCK FOR MULTITURN SHAFTS Filed Dec. 13, 19562 Sheets-Sheet 1 INVENTOR. 1.50 R. KnLous Arronmsvs Oc 27, 1 5 L. R.KALOUS 2,909,933

DIAL SYSTEM WITH LIMIT AND LOCK FOR MULTITURN SHAF'TS Filed Dec. 13,1956 2 Sheets-Sheet 2 IOJ INVENTOR. Lso R KALous wwi Mu.

United States Patent G DIAL SYSTEM WITH LIMIT AND LOCK FOR MULTITURNSHAFTS Leo R. Kalous, Cedar Rapids, Iowa, assignor to Collins RadioCompany, Cedar Rapids, Iowa, a corporation of Iowa Application December13, 1956, Serial No. 628,143

3 Claims. (Cl. 74-102) This invention relates to dial systems and moreparticularly to end-stop systems adaptable to rotating multiturn loads.

In prior art dial systems the usual practice has been to put limit stopson the load rotated, such as a multiturn inductor, capacitor, orresistor. The knob at the front panel is then geared down so that theaccompanying dial is moved in a fashion consistent with the input. As aconsequence of the gearing, however, the stops have an elastic feel atthe knob as a result of a disadvantageously high gear ratio. Carelesshandling results in breakage at the stops or damage to the gear train. Asimilar difficulty arises in position locks when the load itself islocked in place by a panel-actuated knob.

Accordingly, it is an object of the invention to provide bothdirect-acting limit stops and a lock for a multiturn load, the loadturns being related to the dial by a gear It is a further object of .theinvention. to provide a limit stop system which is crisp and certain inits feel at the front panel knob.

It is a further object of this invention to provide a multiturn loadsingle-turn dial system which is relatively simple and easy tomanufacture, yet which is reasonably foolproof in use.

- It is 'a feature of the invention that an epicyclic gear train isutilized to make available to the designer a wide range of gear ratiosof which one can be selected for the particular task, e.g., between tenand one hundred, providing for a directly-driven multiturn load withonly a single turn dial.

It is a further feature of this invention that the system lends itselfto disassembly from the front panel.

Further objects, features, and advantages of ,the invention will becomeapparent from the following description andclaims-when read inconjunction with the drawings, in 'which: p

Figure 1 shows an exploded isometric view of the invention, v

Figure 2 shows a plan view of a portion of Figure 1 including thelocksystem, and s I p Figure 3 shows a side view of Figure 2 showingmore clearly the lock system.

In Figure 1 a majority of the system is mounted on or adjacent to aframe 10. Parallel to saidv frame is a front panel 11 which is spacedfrom frame 10. The upper surface of the front panel 11 is external ofthe equipment. Here a dial 12 is provided having next to it a coaxialknob 13. Dial 12 has indicia on it reflecting the full extent ofrotation relative to an indicator mark 14.

A shaft 16 extends through frame towards the rear of the apparatus forcoupling to a multiturn loadsuch as a rotary inductor which is turned amultiplicity of full turns e.g., from thirty to one hundred times, forfull inductancevariation. The front knob 13 is directly mounted on loadshaft 16. Concentric to load shaft 16 is a fixed gear 17 which ismounted on frame 10. Meshing with gear 17 is a pair of epicyclic gears18 and 4 rate.

Patented Oct. 27, 1959 19. Gear 18 meshes with fixed gear 17 and iscoupled to gear 19. Gear 19 meshes with dial gear 21. The epicyclicgears are mounted on an axle 22 which is carried on gear carrier 23.Epicyclic gears 18 and 19 are free to rotate on their axle 22. Theepicyclic gear carrier 23 is mounted on load shaft 16 and fixed theretoso that it rotates with said shaft. Also mounted rigidly. to gearcarrier 23 is stop wheel 24. The ratio of turns between shaft 16 and theslightly less than one turn of the dial shaft is established by thedesired number of turns of the load between stops. I

Stop wheel 24 is of constant radius throughout most of its circumferenceexcept for two portions 25 which are cut inward radially to provideradial stop faces 26. As can be seen in the drawing, these radialincursions and stop faces are symmetrical with respect to rotation. Dialgear 21 is mounted on a dial shaft 27, which is hollow to permit theload shaft 16 to extend coaxially through it. Also mounted on and fixedto shaft 27 is a control disc cam 28. Cam 28 has a substantiallyconstant radius throughout most of the circumference except in a smallportion 29 where a rotationally symmetrical radial incursion occurs. Theslopes of the radial incursion are smooth with a gradual rise for gentlecamming action, Where the constant radius of stop wheel 24 is less thanthe constant radius of cam 28, such that the stop wheel incursions donot act as the stop pin lift- Dial shaft 27 is parted. by a transverseV-shaped notch 30 for detachable coupling to a separated portion 31 ofthe dial shaft on the front of the front panel. On the separated portion31 is mounted the dial 12. Under knob 13, compressed between knob 13 anddial 12, is a dial spring 32 which presses shaft 31 into the V, 30. Thispermits a satisfactory coupling of the 'dial to the mechanism with asimplified way for disassembly of the front panel from the frame forservicing and further disassembly of the mechanism.

In operation of the load by knob 13, rotation of knob 13 rotates loadshaft 16 and the load directly. This retation turns also gear carrier23.

-As gear carrier 23 is turned, epicyclic gears 18 and 19 are draggedaround the peripheries of gears 17 and 21. As a consequence of the gearshaving dissimilar numbers of teeth, gear 21 is turned at a ratedifferent from that of carrier 23 to turn dial shaft 27 at a slow Asdial gear 21 is rotated at a reduced speed, so also is dial 12 rotatedby its coupling through the V notch 30. I

The rest of the stop system involves a stop plate 40 having fixedthereon a follower and stop pin 41. Stop plate 40 is mounted by means oftwo slots. One is a shaft slot 42 which is an elongated hole which iswide enough to clear shaft 27 and which is just long enough to permitthe stop pin to move in and out of engagement with the stop faces 26 onstop wheel 24. A second slot 43 is similarly proportioned for mountingon fixed post 44 to provide the rotational rigidity necessary for thestop action. Cam follower tension spring 46 is attached between amounting post 47 fixed to stop plate 40 and a retainer ring or washer 48which sets into a notch 49 on hollow dial shaft 27. A washer andretainer 51 engages the end of fixed post 44 for retention of the stopplate on the fixed post.

In operation, the cam follower spring 46 pulls the stop plate 40 towardsthe shaft 27. This causes follower and past follower and stop pin 41,there is no interference. Between stops, the follower pin rides on theconstant radius portion of the control disc 28. At the ends the moreslowly moving control disc campermits the fol- 'lower.pin '41 to dropinto aperture 29. Simultaneously, one of the stop faces 26 approachesand meets the stop :pin, the radial incursion 25 permitting the followerpin 41 -to move in radially, stopping rotation of load shaft 16. It isreadily seen that the interference of rotation of stop wheel 24 by stoppin 41 is direct, stop plate 40 being mountedon the frame and the gearcarrier 23 :nio'ving at the load speed, leaving no gear reduction be-;tween the knob 13 and the stop pin. As a result of this arrangement,the stopping action is direct and crisp and WithOllt any interveninggear train to make the stop feel mushy. It is'a'lso apparent thatrotation of knob 13 away fro the stop causes the rise of the controldisc cam 28 or the incursion 25 to lift the stop pin 41 radially outwardaway from the stop wheel 24 dependent 'on the gear ratio,

to permitrotation away from the stop. As a consequence of the rotationalsymmetry of the control disc 28 for the stop wheel 24, theabove-described action occurs for "either direction of rotation to thedesired end limits.

-along a chord of the gear carrier 23.

The end of the clamp strap 50 is energized at 52 fo'r locking, as seenmore clearly in Figure 3. Strap 50 is bent not only laterally into abroad V, but into a shallow U at '53. The bottom of this shallow U bearsagainst gear 'carrier 23. For locking, end 52 is pushed towards frame 10so as to drive the bottom of the shallow U 53 against the gear carrier.This conformation of the 'clamp strap 50 is such as to give itconsiderable resilience. This resilience makes a contact with gearcarrier 23 having such a friction force as to make rotation with knob 13very difiicult. This results in a very simple and yet very reliable loadposition lock.

The actuator at the end 52 of the lock strap is a threaded shaft 55which is mounted within a triple "threaded nut 56. Thus, to lock, shaft55 is rotated by a panel knob 57 to move inwardly against strap end 52at a relatively fast rate. Double or quadruple threads may be used ifdesired but triple threads give a relatively fast rate of advance tomake the lock effective within a turn of knob 57. This permits the useof a mark on the to particular embodiments thereof, it is not to be so.

limited as changes and modifications may be made therein whicharewithin. thefull intended scope of theinvention as defined by theappended claims.

I claim:

l. A rotational limiting system for a multiturn control shaftcomprising, a bidirectional load shaft having a predetermined limit ofrotation in each direction, a stop wheel fixed coaxially to said controlshaft, a stop pin, means formounting'said stop-pin rigidlycircumferentially with respect to said "stop 'wheel, a rotatable camconnected through an epicyclic gear system to said loa'cl shaft, meansfor rotating said shaft in either direction,

said cam being rotated by said epicyclic gear system in response to therotation of said shaft at a rate-different from that of the rotation ofsaid shaft, means responsive to the rotation of said cam over apredetermined range for moving said stop pin radially to engage acircumferential face of said stop wheel, a stop face projecting radiallyfrom said face of said stop wheel, and said predetermined limits ofrotation being positively determined by the engagement of said stop faceby said stop pin.

2. A rotational limiting system for a multiturn load comprising, abidirectional load shaft having a predesaid stop wheel, means for urgingsaid pin inwardly 'againstthe circumferential edge 'of said control disccam,

means for rotating said load 'shaft' in either direction, the gear'ratio of said'coaxial fixed gear to said epicyclic gear being differentfrom the gear ratio of said epicyclic gear to said coaxial rotatablegear so that the control disc cam is rotated at a different rate fromthat of said stop wheel in response to rotation of said load shaft, saidcontrol disc cam having a radial incursion for permitting said pin toengage the edge of said stop wheel over a predetermined range ofrotation of said control disc'cam, a stop face projecting radially fromsaid edge of said stop wheel, and said predetermined limits of rotationbeing positively determined by the engagement of said stop face withsaid stop pin.

3. A rotation limit system as claimed in claim 2 in combination with alocking means, said locking means being operable for engaging said gearcarrier to lock said load shaft in any selected position.

References Cited in the file of this patent UNITED STATES PATENTS2,496,455 Elliot Feb. 7, 1 950 2,662,422 McGowcn Dec. 15, 1953 2,716,896Beldt et al. Sept. 6, 19

